Electric steam generator



Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE ELECTRIC STEAM GENERATOR Application March 31, 1936, Serial No. 71,881

6 Claims.

-My invention relates to an improvement in electric steam generators, and has for one of its objects the provision of a steam generator capable of generating superheated steam instantaf, neously within definite temperature limits, the electric input being temperature controlled and relatively small; the apparatus provides for relatively large intermittent superheated steam output.

My improved apparatus has a great variety of uses as, for example, in connection with sterilizing, cleaning, steaming of fabrics, spraying metals, etc.

Prior to my invention the universal practice'in steam generator construction and operation been to introduce the feed water into thelowest part of the heat accumulator. .t will be evident that in such arrangements there will be sudden withdrawal of large amounts of heat from the lowest part of the apparatus, which causes quick cooling and eventually stops evaporation until the water level rises or until heat can be transferred to this point. This impairs continuous steam flow, causes surging and bumping; while at the same time a certain amount of water will be left in the accumulator at the end of the withdrawal of steam. This water will gradually evaporate and escape of steam at the open steam outlet of the device, or if this outlet be closed it may cause considerable pressure to be set up within the ap paratus and associated pipelines.

In my improved apparatus I propose to introduce the feed water at the top, the fluid passages being inclined toward the bottom of the appa- I ratus, thereby first cooling down the top of the apparatus, the fluid flowing by gravity to a hotter part of the apparatus until evaporated. lhis is a very fast process. as will he and it will be evident, furthermore, involves having the fluid seeking heat as distinguished from the heat seeking the fluid as in those devices above mentioned in which the feed water is introduced at the bottom.

A further improved feature in connection with. my apparatus is the use of a temperature control device for the definite control of a metal entering into the construction of my apparatus. This temperature control is not only dependent upon the temperature of this metal mass but 50 operates to close the heater circuit whenever feed water enters the steam generator.

In the accompanying drawing:

Fig. 1 is a sectional elevational view of an em bodiment of my invention;

Fig. 2 is a section on the line 2-2 of Fig. 1; and

Fig. 3 is a detail in section of the temperature control device.

Referring to the drawing in detail, I designates a metal mass, a metal casting for example, which as illustrated takes the form of a cylindrical copper casting into which is cast a helical steel tubing 2 constituting the evaporating surface of my generator.

Extending downwardly into the metal mass I so as to be surrounded by the helix of the'tubing 2 is a cartridge heating unit 3. This unit is of well known construction and is preferably cast in place.

Below the lower end of the cartridge heating unit is an equalizing chamber and water trap 4, the structure providing this chamber being cast into the metal mess I. The lower end 5 of the tubing or evaporating surface 2 communicates with an inlet 6 of the equalizing chamber 4, while the outlet 7 of this chamber is in constant communication with superheater' tubing 8 cast into the lower end of the metal mass 1, and disposed in a short lay helix, the lower end of this superheater tubing extending at 9 to the outside of the apparatus.

The upper end of the tubing 2 is coupled to feed-water pipe or tube It which enters the top of the apparatus and is coiled as shown at II about a temperature control chamber It.

The apparatus thus far described is heat insulated with magnesia, asbestos or other suitable heat insulation I 3 and enclosed in a tight fitting metal casing M, It will be noted also that the feed water tubing ill and outlet tubing 3 are heat insulated.

The temperature control chamber I2 is heat insulated from the metal mass l and from the cartridge heating unit by magnesia or other suitable heat insulation l5.

I also preferably provide a groove in the wall of the metal mass l as shown at [6 which I may fill with asbestos or other suitable heat insulator 61, this arrangement reducing the mass of metal adjacent the ieedwater inlet and reducing surg ing and bumping when the apparatus is in use.

In the temperature control chamber I2 I mount suitable automatic electrical control apparatus, one form of which is shown in Fig. 3. This device consists of two round discs l8 and I9. Riveted to the disc l9 are four ontacts 20 insulated from the disc ill by mica or otherwise. The disc I8 is provided with four holes 2| in register with the contacts permitting the rivet heads to be located without touching the disc.

The plates or discs l8 and I9 are riveted to a stud 22 which is internally threaded. Into this stud fits a threaded shaft 23 carrying a bimetal disc 24 on its lower end, provided on its upper surface with contacts 25 adapted to engage the contacts 20 when the bimetal disc takes the dotted line position shown in Fig. 3.

The leads for the heating unit 3 are designated 26 and 21 and after passing the temperature control switch are led to the outside of the casing l4.

When my improved apparatus is to be used and demand is made for steam, feed water is admitted through inlet l 0. The temperature control device or thermostat of Fig. 3 and which, as will now be understood, controls the temperature of the metal mass i is actuated by the feed water, that is to say, as feedwater' is admitted the thermostat will snap to the dotted line position of Fig. 3 to close a circuit to the heater, it being understood, however, that the thermostat is set always to maintain this metal mass at a certain predetermined minimum temperature. The feedwater entering the generator will absorb the heat of the metal mass I nearest the ieedwater inlet, and flowing downwardly toward the equalizing chamber 5 will have its temperature raised gradually, the metal'mass adjacent the feed water inlet cooling down rapidly on account of the restricted heat conductive area toward the feedwater inlet, obtained by casting in a piece of asbestos, the water temperature gradually increasing as it moves toward the lower end of the evaporating surface. By this arrangement heat is gradually imparted to the water thereby reducing surging and bumping to a minimum.

It will be appreciated of course that the steam entering the equalizing chamber 4 will pass immediately to the superheater tubes 8 there to be superheated and discharged through exit 9 as superheated steam.

It will be appreciated that my invention provides an electric steam generator wherein use is made of a metallic mass in conjunction with an automatic temperature control therefor, to the exclusion of fluid heat accumulators. It will be appreciated also that the metal mass will be maintained at a predetermined temperature at all times.

It will be appreciated also that my invention provides for the generation of superheated steam at definite temperature limits instantaneously, involves relatively small temperature controlled electric input and comparatively large intermittent superheated steam output.

It will be apparent also that my improved apparatus provides for introducing the feed fluid at the top, the tubing 2 being arranged so as to slope toward the bottom of the apparatus, insuring more eflicient and noiseless operation.

It will be understood that changes may be made in the detailsof construction and arrangement of parts within the purview of my invention.

It'is to be understood also that types of temperature control apparatus other than that shown and described may be employed without departing from the spirit and scope of my invention.

What I claim is:

1. An electric steam generator comprising a metal mass, tubing constituting the evaporating surface of the generator cast into said metal mass, an electric heater for supplying heat to the generator, a thermostatic control device for said heater adapted to open and close the circuit of said heater at predetermined temperatures of said metal mass, an enclosure for said control device, and a fluid inlet for said tubing coiled about said enclosure so that said control device will close the circuit of said heater immediately upon the admission of fluid to said inlet.

2. An electric steam generator comprising a metal mass, tubing constituting the evaporating surface of the generator cast into said metal mass, said tubing having a fluid inlet at its upper end, an electric heater for supplying heat to the generator, an automatic control device for said heater adapted to open and close the circuit of said heater at predetermined temperatures of said mass, an enclosure for said automatic control device, heat insulation intermediate said metal mass and said control device, said fluid inlet surrounding said enclosure for the automatic control device so that said automatic control device will close the circuit of the heater as fluid passes through said inlet.

3. An electric steam generator comprising in combination an elongated metal mass and metal tubing cast integral with each other, the tubing extending helically of the metal mass and constituting the evaporating surface of the generator, a stationary electric resistance heater extending into said mass so as to be surrounded by said tubing, and an automatic control for the circuit of said heater located adjacent to but heat insulated from said metal mass and from said heater.

4. An electric steam generator comprising in combination a metal mass, tubing cast into said mass and extending helically thereof, said metal mass being provided with a longitudinally extending central space, an electric heating unit extending into said space, a chamber at the lower end of the heating unit with which the lower end of said tubing communicates, tubing below the first mentioned tubing cast into said metal mass and having its upper end in communication with the last mentioned chamber for the generation of superheated steam.

5. An electric steam generator comprising in combination a metal mass, metal tubing cast thereinto and extending helically thereof, an electric heater extending into said metal mass in position to be surrounded thereby and byrsaid.

vided with a central chamber, an electric heater extending into and fitting said chamber to be surrounded by said tubing, a thermostatic control device for said heater located adjacent the top of said metal mass and heat insulated therefrom for maintaining the mass at a predetermined, temperature, an enclosure for said thermostatic control, and an inlet for said tubing coiling about said enclosure to effect operation of said thermostat whereby as'feed-fluid is admitted to the apparatus said thermostat will close the circuit to the electric heater.

KURT BEYRODT. 

